Consider a 20-cm-thick large concrete plane wall (k = 0.77 W/m · K) subjected to convection on both sides with T_∞1 = 22°C and h₁ = 8 W/m²·K on the inside, and T_∞2 = 8°C and h₂ = 12 W/m² · K on the outside. Assuming constant thermal conductivity with no heat generation and negligible radiation,

(a) Express the differential equations and the boundary conditions for steady one-dimensional heat conduction through the wall,

(b) Obtain a relation for the variation of temperature in the wall by solving the differential equation,

(c) Evaluate the temperatures at the inner and outer surfaces of the wall.